This invention relates to a class of Group 4 metal complexes and to olefin polymerization catalysts derived therefrom that are particularly suitable for use in a polymerization process for preparing polymers by polymerization of xcex1-olefins and mixtures of xcex1-olefins, and to the xcex1-olefins and mixtures of xcex1-olefins resulting therefrom.
Constrained geometry metal complexes and methods for their preparation are disclosed in EP-A416,815; EP-A-468,651; EP-A-514,828; EP-A-520,732 and WO93/19104, as well as U.S. Pat. No. 5,055,438, U.S. Pat. No. 5,057,475, U.S. Pat. No. 5,096,867, U.S. Pat. No. 5,064,802, U.S. Pat. No. 5,132,380, U.S. Pat. No. 5,470,993, WO95/00526, and US Provisional Application 60-005913. Variously substituted indenyl containing metal complexes have been taught in U.S. Ser. No. 592,756, filed Jan. 26, 1996, as well as WO 95/14024. The teachings of all of the foregoing patents or the corresponding U.S. patent applications are incorporated herein by reference in their entirety.
Constrained geometry catalysts and other single site or metallocene catalysts are useful to prepare homogeneous olefin polymers. The term xe2x80x9chomogeneous olefin polymersxe2x80x9d refers to homopolymers or interpolymers of one or more xcex1-olefins which are characterized as having a narrow polydispersity, i.e., an Mw/Mn of from 1.5 to 3.0, and, in the case of interpolymers, a homogeneous short chain branching distribution, i.e., wherein each molecule has substantially the same number of short chain branches. Homogeneous olefin polymers are advantageous over Ziegler Natta produced polymers, in that they lack a low molecular weight tail fraction, which translates to improved strength and toughness. Homogeneous olefin polymers are further advantageous over Ziegler Natta produced polymers, in that the catalysts useful to prepare such polymers, particularly the constrained geometry catalysts, readily and efficiently incorporate comonomer, which permits the cost-effective production of polymers having a density of less than 0.910 g/cm3 which accords good elastomeric properties.
Despite their advantageous features, homogeneous polymers are typically more difficult to process than their Ziegler Natta counterparts, in part due to the absence of the low molecular weight fraction and in part due to the narrowness of the melting region.
One preferred class of homogeneous olefin polymers is the class of substantially linear polymers, which are characterized as having a narrow polydispersity, a homogeneous short chain branching distribution, and the presence of sufficient long chain branching to provide improved rheological properties and resistance to melt fracture. Substantially linear polymers are disclosed and claimed in U.S. Pat. Nos. 5,272,236; 5,278,272; 5,380,810; and EP 659,773; EP 676,421; and WO 94/07930.
An alternate approach to utilizing the preferred substantially linear olefin polymers has been to incorporate into homogeneous olefin polymers effective amounts of polymer processing aids prior to fabrication into films or articles. This is disadvantageous, in that it requires an additional processing step and adds cost to the finished product.
While homogeneous olefin-based elastomers, and particularly substantially linear olefin polymers, have found significant commercial utility, the low density of the elastomers, coupled with the absence of a higher crystallinity non-short chain branched fraction renders such polymers relatively poor in terms of upper service temperature and susceptible to deformation under heat, such as in a clothes dryer.
To improve the upper service temperature of homogeneous olefin polymers which are elastomers, one can blend such polymers with higher crystallinity homogeneous or heterogeneous olefin polymers, either via a physical blend or via an in-reactor mixture produced in a dual reactor system, such as is disclosed in U.S. Ser. No. 510,527, filed on Aug. 2, 1995 (WO 94/171112) and U.S. Ser. No. 208,068, filed on Mar. 8,1994 (EP 619827), each of which is incorporated herein by reference in its entirety.
However, industry would find great advantage in a polymer having elastomeric properties which exhibits a resistance to deformation under heat which is greater than that of a physical or in-reactor blend of the same overally density. Industry would find particular advantage in those of such polymers which have an overall polydispersity of from 1.5 to 3.0, but which have excellent processability, as evidenced by resistance to melt fracture and/or an I10/I2 of at least 10. Industry would find especially particular advantage in those of such polymers which may be produced in a single reactor using a highly efficient catalyst which is resistant to degradation at elevated temperature.
It is noted that U.S. Pat. No. 5,621,126 to Exxon Chemical Patents, Inc., discloses the use of mono(cyclopentadienyl) Group IV B metal compounds to produce ethylene/xcex1-olefin copolymers. U.S. Pat. No. 5,621,126 asserts that catalysts containing an amido group having a hydrocarbyl ligand Rxe2x80x2 which is aliphatic or alicyclic and which is bonded to the nitrogen atom through a primary or secondary carbon produce copolymers having a greater degree of xcex1-olefin incorporation than catalysts wherein the hydrocarbyl ligand Rxe2x80x2 is bonded to the nitrogen atom through a tertiary carbon atom or wherein Rxe2x80x2 bears aromatic carbon atoms. U.S. Pat. No. 5,621,126 asserts that when the Rxe2x80x2 ligand is bonded to the nitrogen atom through a secondary carbon atom, the activity of the catalyst is greater when Rxe2x80x2 is alicyclic than when Rxe2x80x2 is bonded to the nitrogen through a primary carbon atom of an aliphatic group of identical carbon number. U.S. Pat. No. 5,621,126 asserts that as the number of carbon atoms of Rxe2x80x2 thereof increases, the productivity of the catalyst system and the molecular weight of the ethylene/xcex1-olefin copolymer increase while the amount of xcex1-olefin comonomer incorporated remains about the same or increases. U.S. Pat. No. 5,621,126 asserts that the more preferred Rxe2x80x2 ligand is cyclododecyl.
The compositions of U.S. Pat. No. 5,621,126 are disadvantageous, in that they are believed to lack long chain branching, making them susceptible to melt fracture, and thus, less commercially desirable.
Further, while mono(cyclopentadienyl) Group IV B metal compounds may indeed find great commercial advantage in the polymerization of ethylene/xcex1-olefin interpolymers, those in industry are continually seeking improvements and, in particular, would find advantage in catalysts which withstand higher reaction temperatures than are characteristic of bmono(cyclopentadienyl) catalysts. Such higher reaction temperatures would translate to polymers exhibiting a high degree of vinyl unsaturation, making them especially useful as precursors to functionalized polymers, and enhancing long chain branch incorporation when appropriate polymerization conditions are employed.
According to the present invention there is provided a product produced by a process for preparing polymers of olefin monomers comprising contacting one or more such monomers with a catalyst comprising:
1) a metal complex corresponding to the formula: 
xe2x80x83wherein:
M is titanium, zirconium or hafnium in the +2, +3 or +4 formal oxidation state;
Axe2x80x2 is a substituted indenyl group substituted in at least the 2 or 3 position with a group selected from hydrocarbyl, fluoro-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, dialkylamino-substituted hydrocarbyl, silyl, germyl and mixtures thereof, said group containing up to 40 nonhydrogen atoms, and said Axe2x80x2 further being covalently bonded to M by means of a divalent Z group;
Z is a divalent moiety bound to both Axe2x80x2 and M via "sgr"-bonds, said Z comprising boron, or a member of Group 14 of the Periodic Table of the Elements, and also comprising nitrogen, phosphorus, sulfur or oxygen, wherein Z preferably has covalently bonded thereto an aliphatic or cycloaliphatic hydrocarbyl or substituted hydrocarbyl group, such that the hydrocarbyl group is covalently bonded to Z via a primary or secondary carbon;
X is an anionic or dianionic ligand group having up to 60 atoms exclusive of the class of ligands that are cyclic, delocalized, xcfx80-bound ligand groups;
Xxe2x80x2 independently each occurrence is a neutral ligating compound, having up to 20 atoms;
p is 0, 1 or 2, and is two less than the formal oxidation state of M, with the proviso that when X is a dianionic ligand group, p is 1; and
q is 0, 1 or 2; and
2) an activating cocatalyst
the molar ratio of 1) to 2) being from 1:10,000 to 100:1, or
the reaction product formed by converting 1) to an active catalyst by use of an activating technique.
Also disclosed is a product produced by a process comprising reacting one or more xcex1-olefins in the presence of a catalyst which in turn comprises a metal complex corresponding to the formula: 
where M is titanium, zirconium or hafnium in the +2, +3 or +4 formal oxidation state;
Rxe2x80x2 and Rxe2x80x3 are independently each occurrence hydride, hydrocarbyl, silyl, germyl, halide, hydrocarbyloxy, hydrocarbylsiloxy, hydrocarbylsilylamino, di(hydrocarbyl)amino, hydrocarbyleneamino, di(hydrocarbyl)phosphino, hydrocarbylene-phosphino, hydrocarbylsulfido, halo-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, silyl-substituted hydrocarbyl, hydrocarbylsiloxy-substituted hydrocarbyl, hydrocarbylsilylamino-substituted hydrocarbyl, di(hydrocarbyl)amino-substituted hydrocarbyl, hydrocarbyleneamino-substituted hydrocarbyl, di(hydrocarbyl)phosphino-substituted hydrocarbyl, hydrocarbylene-phosphino-substituted hydrocarbyl, or hydrocarbylsulfido-substituted hydrocarbyl, said Rxe2x80x2 or Rxe2x80x3 group having up to 40 nonhydrogen atoms, and optionally two or more of the foregoing groups may together form a divalent derivative;
Rxe2x80x2xe2x80x3 is a divalent hydrocarbylene- or substituted hydrocarbylene group forming a fused system with the remainder of the metal complex, said Rxe2x80x2xe2x80x3 containing from 1 to 30 nonhydrogen atoms;
Z is a divalent moiety, or a moiety comprising one "sgr"-bond and a neutral two electron pair able to form a coordinate-covalent bond to M, said Z comprising boron, or a member of Group 14 of the Periodic Table of the Elements, and also comprising nitrogen, phosphorus, sulfur or oxygen;
X is a monovalent anionic ligand group having up to 60 atoms exclusive of the class of ligands that are cyclic, delocalized, xcfx80-bound ligand groups;
Xxe2x80x2 independently each occurrence is a neutral ligating compound having up to 20 atoms;
Xxe2x80x3 is a divalent anionic ligand group having up to 60 atoms;
p is zero, 1, 2, or 3;
q is zero, 1 or 2, and
r is zero or 1; and
2) an activating cocatalyst
the molar ratio of 1) to 2) being from 1:10,000 to 100:1, or
the reaction product formed by converting 1) to an active catalyst by use of an activating technique.
The present catalysts and process employed in the polymerization of the polymers of the invention, preferably by means of a solution polymerization process, result in the highly efficient production of high molecular weight olefin polymers, particularly ethylene/xcex1-olefin interpolymers, ethylene/propylene/diene interpolymers (EPDM), wherein the diene is ethylidenenorbomene, 1,4-hexadiene, or a similar nonconjugated diene, or is piperylene, over a wide range of polymerization conditions, and especially at elevated temperatures. The use of elevated temperatures dramatically increases the productivity of such process due to the fact that increased polymer solubility at elevated temperatures allows the use of increased conversions (higher concentration of polymer product) without exceeding solution viscosity limitations of the polymerization equipment as well as reduced energy costs needed to devolatilize the reaction product.
The subject invention further provides an olefin interpolymer, preferably an interpolymer of ethylene and at least one C3-C20 xcex1-olefin, characterized as satisfying at least four of the following criteria, especially all five of the following criteria:
a) an I2xe2x89xa6100 g/10 min,
b) an Mw/Mn of from 1.5 to 3.0,
c) at least 0.03 vinyls/1000 carbons, as determined by FTIR, and
d) at least two distinct ATREF peaks, each of which satisfies the following inequality:
ATREF Shape Factorxe2x89xa60.90xe2x88x920.00626 (Average Elution Temperature).
The use of the indenyl and indecenyl catalysts as disclosed herein leads to the production of polymers having a high degree of vinyl termination. The resultant high level of vinyls/1000 carbons makes the polymers of the invention especially useful in applications wherein the polymers are subsequently functionalized. The resultant high level of vinyls/1000 carbons further makes the polymers able to achieve higher levels of long chain branching when appropriate polymerization conditions are employed.
Preferably, the polymers of the invention will be characterized as having an I10/I2 of at least 10, preferably at least 12, and most preferably at least 15.
As further qualitative indicia of long chain branching, the polymers of the invention will preferably further be characterized as exhibiting a critical shear rate at the onset of surface melt fracture which is at least 50 percent greater than the critical shear rate at the onset of surface melt fracture for a linear interpolymer, wherein the substantially linear interpolymer and the linear interpolymer comprise the same comonomer or comonomers, the linear interpolymer has an I2, Mw/Mn and density within ten percent of that of the substantially linear interpolymer, and wherein the respective critical shear rates of the substantially linear interpolymer and the linear interpolymer are measured at the same melt temperature using a gas extrusion rheometer.
The olefin interpolymers of the invention are uniquely characterized as being bimodal with respect to the short chain branching distribution and molecular weight, as evidenced by the differential scanning calorimetry and ATREF curves, as well as the deconvoluted gel permeation chromatographs. This effect is particularly true for interpolymers having a density of no more than 0.910 g/cm3.
It has been found that interpolymers of the invention having a density less than 0.890 g/cm3, particularly having a density of no more than 0.880 g/cm3, and more particularly having a density of less than 0.870 g/cm3 have a particularly superior and highly unique balance of properties. In particular, such polymers have improved elastomeric properties, such as a compression set of less than 90 percent, preferably less than 85 percent, more preferably less than 80 percent, coupled with an upper service temperature which exceeds that of a physical blend of interpolymers corresponding to the components of the interpolymers of the invention as discerned by the deconvolution of the representative gel permeation chromatograph. The uniqueness of the interpolymers of the invention is evident in micrographs obtained by transmission electron microscropy, which clearly show the presence of lamella in interpolymers whose density would suggest should be wholly amorphous.
The olefin interpolymers of the invention are expected to have great utility in a variety of applications, including but not limited to films, fibers, foams, injection molded parts, rotational molded parts, and as components of formulations such as adhesives, sealants, coatings, caulks, asphalt, etc.